Means for securing printing plates to their cylinders



NOV. 7, 1944'.` H M BARBER 2,361,919

MEANS FOR SECURING PRINTING PLATES TO THEIR CYLINDERS Filed Nov. 13, 1941 INVENTOR. M MM www Patented Nov. 7, 1944 MEANS FOB SECUBING PRINTING PLATES l T THEIR CYLINDERS Howard M. Barber, Paweatuok, Conn., assignor to C. B. Cottrell 80m C ompany, Westerly, B. I.,

acorporation of Delaware Application November 18, 1941, Serial No. 418,941

(Cl. lill-378) 4Claims.

In rotary printing presses which require plates to be attached to the form cylinder it is customary to bevel both the curved edges and the straight edges of the printing plates so that when the plates are attached to a cylinder having the usual annular series of spiral grooves the plate clamps which are adjustable in the spiral grooves will be caused to engage the beveled straight edges as Well as the beveled curved edges of the said plates. The location of these clamps along the straight edges of the plates necessarily renuire a considerable spacing of the plates around the cylinder, thereby requiring the use oi' a considerable amount more of the paper than'i! the printing plates could be positioned closely to" gather around the cylinder. This is especially true when. running full bleed magazine pages or when running the conventional labels which usually have all-over printed backgrounds.

One object of my invention is to provide novel means for accurately positioning the printing plates on the cylinder and holding them in such position against the crowd of printing pressure which would tend to move the plates slightly out oi position around the cylinder.

another object is to save paper by eliminating the plate clamps along the straight edges of the plates and thus permitting the mounting' oi the plates closely together around the cylinder.

My invention comprises, generally, the provision oi means for interlocking the backs of the plates with the cylinder, such interlocking means serving also to properly position the plates and eliminate the requirement of clamps along their adjacent straight edges.

li/iy invention more specifically comprises the provision oi straight grooves across the backs oi the plates, which gooves are brought opposite corresponding grooves formed in the cylinder parallel to its axis, in which corresponding grooves keys are located for not only positioning the plates on the cylinder but also holding them against movement around the same. It is to be understood that the usual plate clamps are provided for engaging the curved edges only oi the plates to secure them to the cylinder in their proper relative positions.

.it practical embodiment of my invention is represented in the accompanying drawing, in which iig. l represents a detail face view of a printing cylinder with plates positioned thereon by my novel means;

Fis. 2 represents a longitudinal section taken in the plane of the line H--II of Fig. l, looking in the direction of the arrows;

Fig. 3 represents a transverse section taken in the plane of the line III--III of Fig. 1, looking in the direction ofthe arrows;

Fig. 4 represents a back view of a printing plate showing the straight groove across the same; and

Fig. 5 represents an edge view of the printing plate.

The form cylinder I is shown as having the usual annular series of spaced spiral grooves 2 along which the usual plate clamps 3 are moved into proper position to engage the curved edges only of the imposed printing plates and thus secure the plates on the cylinder. This form cylinder is also provided with one or more grooves t extending parallel to the axis of rotation of the cylinder. In the present instance I have shown an annular series of equally spaced straight grooves crossing the spiral grooves 2.

Each oi the imposed curved printing plates 5 is provided with beveled curved edges 6 and squared straight edges l. These squared straight edges permit the printing faces of two circumferential adjacent plates to be brough closely together, it being understood that the clamps t are caused to engage the beveled curved edges of the plate to secure it to the face of the cylinder.

The back of each of the curved printing plates t has a groove extending across the saine parallel to the straight grooves 4 along the cylinder and opposite a selected one oi.' the said straight cylinder grooves. These straight plate grooves t in the several plates are located at predetermined distances from the straight edges oi' the plates so as to bring the plate grooves opposite one of the spaced straight grooves 4 in the cylinder irrespective oi the circumferential lengths of the plates. This permits printing plates oi diilerent circumferential lengths to be properly positioned and alined around the cylinder.

It will be understood that the grooves in the backs ci' one rov;r of printing plates arranged lengthwise of the cylinder will be in alinement and that, because of the iixed distances between the straight cylinder grooves, the grooves in the backs of another row of printing plates arranged lengthwise of the cylinder will be in alinement but may not have the same location on the plates as the alined grooves in the backs of the rst row of plates. This would be true even though all oi' the printing plates of the form were of the same circumferential length.

'I'he means which I have provided for positioning the plates and holding them against the crowd of the printing pressure tending to move the plates around the cylinder. are removable keys l which closely nt in their respective grooves along the backs of the plates'and in the corresponding opposite grooves in the cylinder. One or more keys may be used for this purpose.

It will be understood that in grooving the backs of the plates to register the plates on the cylinder and to hold them against movement around the cylinder, the combined registry and holding grooyes l are cut across the plates in a prede terrnined relationship to the center lines of the plates, such center lines being indicated, in the present instance, by the marks il.

From the above description it will be seen that I have not only provided means for properly positioning the plates, both'lengthwise of the cylinder and around the cylinder, but I am also enabled to use such means for holding the plates against movement around the cylider due to the crowding of the printing pressure. It will also be seen that I am enabled to eliminate the plate clamps along the straight edges of the plates and thus allow the plates to be brought into close proximity to each other, around the cylinder.

It is evident that various changes may be resorted to in the construction, form and arrangement of the several parts without departing from the spirit and scope of my invention, and hence I do not intend to be limited to the particular embodiment herein shown and described, but what I claim is:

1. A plate cylinder having an annular series of spaced spiral grooves, imposed curved printing plates of predetermined circumferential lengths arranged around the cylinder with their adjacent straight unsecured edges close to each other, clamps adjustable along said spiral grooves for engaging the curved edges of the plates and serving as the only means for securing the plates to the cylinder, and means engaging the cylinder and the backs of the plates at equally spaced intervals around the cylinderdrrespective of the circumferential lengths of the plates for positioning the plates and holding them against movement around the cylinder.

2. A plate cylinder having an annular series 4 inder with their adjacent unsecured straight' of spaced spiral grooves. imposed curved print ing plates of predetermined circumferential lengths arranged 'lengthwise o f and around the cylinder with their adjacent straight unsecured edges close to each other, clamps adjustable along said spiral grooves for engaging the curved edges of the plates and serving as the only means for securing the'plates to the cylinder, and means engaging the cylinder and the backs of the plates at equally spaced intervals around the cylinder irrespective of the circumferential lengths of the plates for positioning the plates and holding them against movement around the cylinder.

3. A plate cylinder having an annular series of spiral grooves and also having an annular'v series of equally spaced straight narrow grooves, imposed curved printing plates of predetermined circumferential lengths arranged around the cyledges close to each other and having equally spaced straight narrow grooves across their backs opposite their respective cylinder grooves, clamps adjustable along said spiral grooves for engaging the curved edges of the plates and serving as the only means for securing the plates to the cylinder, and keys in opposite grooves of the plates and cylinder for positioning the plates and holding them against movement around the cylinder.

4. A plate cylinder having an annular series of spiral grooves and also having an annular series of equally spaced straight narrow grooves, imposed curved printing plates of predetermined circumferential lengths arranged lengthwise of and around the cylinder with their adjacent unsecured straight edges close to each other and having equally spaced straight narrow grooves across their backs opposite their respective cyl inder grooves, clamps adjustable along said spiral grooves for engaging the curved edges of the plates and serving as the only means for securing the plates to the cylinder, and keys in opposite grooves of the plates and cylinder for positioning the plates and holding them against movement around the cylinder.

HOWARD M. BARBER. 

